This proposal is for an interdisciplinary program of research involving a collaboration among a group of biological and clinical scientists. The possible role of various central neurotransmitter systems in mediating mental and behavioral phenomena will be investigated. The program will be directed particularly toward possible disturbances in the function of dopamine, serotonin and acetylcholine in the pathogenesis of psychotic symptoms and in the mediation of the action of psychotropic drugs. Relevant metabolism, receptor mediated functions and cellular systems supporting neuronal transmission will be studied. Specific attention will be given to aspects of these functions which can be manipulated in the development of new therapeutic strategies. Psychological studies will be carried out in an attempt to develop further insight into the possible locus of central abnormalities associated with functional psychotic disorders. Quantitative behavioral assessment techniques will be further developed and evaluated, and applied in the conduct of clinical studies.